Compound for retarding combustion of polycarbonamides

ABSTRACT

Sulfanilate salts of guanidine and guanylurea, useful as flameretardants for synthetic polymeric resins. Incorporation of such salts into, for example, polycarbonamides, produces a selfextinguishing flame-resistant composition.

0 United States Patent 1 [1 11 3,718,658 Summers 1 Feb. 27, 1973 54 COMPOUND FOR RET RDIN 2,482,755 9 1949 Ford et al ..8/116.2

2,488,034 11/1949 Pingree et al ..1 17/136 POLYCARBONAMIDES OTHER PUBLICATIONS [75] Inventor: John C. Summers, Wilmington, Del. p Kaner et al Hewetica Chimica Acta" 24 [73] Assignee: E. I. du Pont de Nemours and Com- 3104110941) W'l t l. puny 1 mmg De Primary Examiner-Leon Zitver [22] F d! J ly 0, 19 Assistant ExaminerLeo B. DeCrescente [21] PP NOI: 54,017 AtzorneyD0n M. Kerr [57] ABSTRACT [52] 260/459 Sulfanilate salts of guanidine and guanylurea, useful as 161/403 flame-retardants for synthetic polymeric resins. Incor- [5 ..C07c po -anon of such alts into for example polycafbona- [58] Field of Search ..260/50l.12 id rodu e a self-extinguishing flame-resistant composition. [56] References Cited 2 Claims, No Drawings UNITED STATES PATENTS 2,520,103 8/[950 MacMillan et al. ..1 17/137 COMPOUND FOR RETARDING COMBUSTION OF POLYCARBONAMIDES BACKGROUND OF INVENTION This invention relates to sulfanilate compounds of guanidine and guanylurea and flame-resistant polycarbonamide compositions containing such compounds.

The literature discloses that phosphates of guanylurea (U.S. Pat. No. 2,488,034) and guanidine (US. Pat. No. 2,520,103) are useful as fiameproofing agents for cellulosic materials. Carbonates and sulfates of guanidine and guanylurea (US. Pat. No. 2,482,755) are also known in the art as combustion inhibitors for both cellulosic and proteinaceous materials. This latter reference also indicates that the disclosed compounds are efiective inhibitors for synthetic materials such as rayon (regenerated cellulose). The primary problem involved in the flameproofing of cellulosic and proteinaceous materials appears, from the literature, to be the prevention of degradation of the fibers and materials by the disclosed agents and processes.

Compatibility of flameproofing agents with polymer, not degradation, appears as the primary problem confronting combustion inhibitor technology with respect to synthetics. Ordinarily, it has required appreciable amounts of flame-proofing agents to impart the desired degree of flame resistance. Because the most efficient and effective method of imparting such protection requires incorporation of inhibitor into the raw polymer, the natural characteristics (clarity, resilience and strength) are somewhat, if not dramatically, altered. There is a pressing need in this area of technology for compounds and techniques that would provide the requisite degree of inhibition while causing the least interference with the natural polymeric properties.

My invention provides these compounds and techniques. The compounds of this invention will impart substantial flame resistance to polycarbonamides at relatively low concentrations, thereby reducing, if not eliminating in most instances, appreciable alteration of natural polymeric properties.

SUMMARY OF INVENTION In summary, the flame-retarding compounds of this invention are of the general formula n is a positive integer from to 4 with the proviso that when n =0, R is DESCRIPTION OF INVENTION Compounds The guanylurea and guanidine sulfanilate salts of this invention can be represented by the formula n is a positive integer from 0 to 4 with the proviso that when n 0, R is Guanylurea compounds of the above formula can be prepared by combining equimolar amounts of guanylurea and the desired sulfanilic acid or sodium salt thereof in an aqueous acidic solution, e.g., hydrochloric acid. The compounds produced by the reaction of these reagents form an insoluble precipitate which can be separated from the reaction medium by filtration, and subsequently purified by recrystallization from water or butanol to remove minor traces of acid and/or sodium salts. The guanylurea reagent of this reaction can be prepared by hydrolyzing cyanoguanidine with an aqueous acid.

The guanidine and guanidinium compounds of this invention can be prepared by merely titrating a basic aqueous guanidine solution with sulfanilic acid to neutrality. As the solvent medium is evaporated, the desired reaction product will form crystals and precipitate. This product can be dissolved and recrystallized in water to enhance its purity.

Representative of the compounds of this invention which demonstrate significant combustion inhibition when applied to, or combined with, synthetic polymeric materials are guanylurea sulfanilate, guanylurea 2,5- dichlorosulfanilate, guanidinium 2-bromo-6- chlorosulfanilate, guanidinium orthanilate, guanylurea metanilate, guanidinium 2-chlorosulfanilate, guanylurea 2-chlorosulfanilate, guanidinium 2bromosu1fanilate, guanylurea 2-bromosulfanilate, guanidinium tetrachlorosulfanilate, guanylurea tetrabromosulfanilate and guanidinium sulfanilate.

The compound guanidinium sulfanilate is old in the art and its preparation has been described as early as 1941 (see Helv. Chim. Acta. 24: 310-31 1). It possesses the same general flame-retardant properties as the novel compounds of this invention; however, these properties, up to now, have remained unappreciated. Polymer The synthetic polymeric materials which can be rendered flame-resistant by the addition of an effective 'amount of the compounds of this invention are This invention also encompasses polycarbonam|de compositions containing an effective amount of the above compounds.

generally known as polycarbonamide; i.e., long-chain synthetic polyamides having recurring amide groups as an integral part of the polymer chain. The preferred polycarbonamides of the flame-resistant compositions of this invention are those which have recurring units of the formula wherein R and R are independently selected divalent hydrocarbon radicals containing about four to 14 carbon atoms, selected from the group consisting of saturated aliphatic and cycloaliphatic radicals, and aromatic radicals, including mixed aliphatic/cycloaliphatic and aliphatic/aromatic radicals. Examples of such polycarbonamides include polycaprolactam (nylon 6) and polyhexamethylene-adipamide (nylon 6,6). Compositions The compounds of this invention, and guanidinium sulfanilate, can be readily combined with polycarbonamides, and hot-pressed or melt-blended into flame-resistant films or fibers.

The amount of flame-retardant necessary to impart flame-resistance to a polycarbonamide composition of this invention will ordinarily range from 0.05 to 5.0 percent by weight of the polymer depending on the particular compound. Concentrations of retardant in such compositions can exceed percent however, as a practical matter, concentrations of flame-retardant compound in excess of this arbitrary level tend to cause interference in the inherent properties of the polymer.

The polycarbonamide compositions of this invention can contain, in addition to the polymer and a flame-retardant compound, other conventional additives, such as delusterants, anti-oxidants, anti-static agents, dye acceptors, and the like.

An effective amount of flame-retardant compound can be dry-mixed with a polycarbonamide, and the resulting mixture hot-pressed or melt blended. After the mixture has become molten, it can be shaped or spun into flame-resistant articles or fibers. Alternatively, an efiective amount of flame-retardant compound can also be stirred into already molten polycarbonamide and substantially the same results achieved. Apparently, the method of combining or blending the flame-retardant and polycarbonamide is not critical so long as there is a uniform dispersion of these sulfanilate compounds throughout the polymer.

Pre-treatment of some of the compounds of this invention prior to admixture with polycarbonamides enhances the compatibility of these two materials. For example, pretreatment of guanylurea sulfanilate by refluxing in a basic aqueous solution makes them more compatible with the polycarbonamide polymer. This improved compatibility is manifested in greater transparency and flexibility of the treated polymer.

The following examples are include to further specifically illustrate the preparation of the compounds and compositions of this invention. Parts and percentages used are by weight unless otherwise stipulated.

EXAMPLE 1 To 316 parts barium hydroxide octahydrate dissolved in 1600 parts water are added 216 parts guanidine sulfate dissolved in 250 parts water. The resulting barium sulfate precipitate is removed by filtration to give a clear guanidine solution. About 310 parts sulfanilic acid are added until pH is about 7. Removal of water and subsequent recrystallization from water gives 289 parts guanidinium sulfanilate, m.p. 2l9221 C. and a second crop of 61 parts, m.p. 2l52l8C. Anal. Calcd. for C H N4O3S: C, 36.20; H, 5.20; N, 24.12 Found: C, 36.08; H, 5.20; N, 24.62

To 9 parts of powdered 66 nylon is added 1 part of guanidinium sulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a transparent, flexible, relatively bubble-free film which is self-extinguishing in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 2 To 16 parts barium hydroxide octahydrate dissolved in 150 parts water are added 15 parts guanylurea sulfate dissolved in 150 parts water. The resulting barium sulfate precipitate is removed by filtration to give a clear guanylurea solution. About 17 parts sulfanilic acid are added until pH is about 7. Removal of water and subsequent recrystallization from water gives 19 parts guanylurea sulfanilate, m.p. ll78 C.

Anal. Calcd. for C H N5O4S: C, 34.90; H, 4.76; N, 25.44 Found: C, 34.64; H, 4.76; N, 25.36

To 9 parts of powdered 66 nylon is added 1 part of guanylurea sulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. On a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a hazy rather poor film which is flame retarding in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 3 To 264 parts 2,5-dichlorosulfanilic acid, sodium salt in 3,500 parts water at C. are added 92 parts cyanoguanidine. parts 37 percent hydrochloric acid are added portionwise, and the reaction is maintained at 90 C. for 3 hours. It is cooled to 25 C., filtered to remove solid, and the solid reheated in 3,500 parts water. Filtration to remove impurities and concentration of filtrate gives parts guanylurea 2,5- dichloro-sulfanilate. Recrystallization from methanol gives solid, m.p. 204206 C.

Anal. Calcd. for C H CI2NSO4S: C, 27.91; H, 3.22; N, 20.35; Cl, 20.60; 0, 18.59; S, 9.32

Found: C, 27.77; H, 3.48; N, 20.37; Cl, 20.30; 0, 19.31;S,9.66

To 9 parts of powdered 66 nylon is added 1 part of guanylurea 2,5-dichlorosulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a film which is somewhat brittle but flame retarding in a vertical match test using a wooden match burning for sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 4 A superior alternative preparation of guanylurea 2,5- dichlorosulfanilate is as follows: An aqueous guanylurea solution is prepared in the usual manner as in Example 2. An equivalent of 2,5-dichlorosulfanilic acid sodium salt is added followed by the addition of hydrochloric acid until the reaction mass is acidic. A solution is then obtained by heating and adding water. Cooling gives guanylurea 2,5-dichlorosulfanilate, m.p. 204-206 C.

EXAMPLE 5 Guanylurea 2,5-dichlorosulfanilate is prepared as in Example 3. Sixty-nine parts guanylurea 2,5- dichlorosulfanilate and five parts 50 percent sodium hydroxide are heated with 800 parts water near reflux for 6 minutes prior to cooling which gives a mixture of guanylurea 2,5-dichlorosulfanilate and partially hydrolyzed material which melts mostly between l90l95 C. This mixture is more compatible with nylon blends than untreated guanylurea 2,5- dichlorosulfanilate.

To 9 parts of powdered 66 nylon is added 1 part of base treated guanylurea 2,5-dichlorosulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a film of good transparency and flexibility which is self-extinguishing in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 6 An aqueous guanidine solution is prepared in the same manner as in Example 1. To an equivalent solution containing 5.9 parts guanidine is added 28.9 parts 2-bromo-6-chlorosulfanilic acid until the pH is about 7. Concentration of solution gives guanidinium 2-bromo- -chlorosulfanilate. 1

To 9 parts of powdered nylon is added 1 part of guanidinium 2bromo-6-chlorosulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum to give a film which is flame retarding in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 7 An aqueous guanidine solution is prepared in the same manner as in Example 1. To an equivalent solution containing 5.9 parts guanidine is added 17.3 parts orthanilic acid until the pH is about 7. Concentration of the solution gives the guanidine salt of orthanilic acid.

To 9 parts of powdered nylon is added 1 part of guanidinium orthanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a film which is flame retarding in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 8 An aqueous guanylurea solution is prepared in the same manner as in Example 2. To an equivalent solution containing 10.2 parts guanylurea is added 17.3 parts metanilic acid until the pH is about 7. Concentration of the solution gives the guanylurea salt of metanilic acid.

To 9 parts of powdered nylon is added 1 part of the guanylurea salt of metanilic acid, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a film which is flame retarding in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 9 An aqueous guanidine solution is prepared as in Example I. To an equivalent solution containing 5.9 parts guanidine is added 20.7 parts 2-chlorosulfanilic acid until the pH is about 7. Concentration of solution yields guanidinium 2-chlorosulfanilate.

To 9 parts of powdered nylon is added 1 part of guanidinium 2-chlorosulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a film which is flame retarding in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 10 An aqueous guanylurea solution is prepared as in Example 2. To an equivalent solution containing 10.2 parts guanylurea is added 20.7 parts 2-chlorosulfanilic acid until the pH is about 7. Concentration of the solution gives guanylurea 2-chlorosulfanilate.

To 9 parts of powdered nylon is added 1 part of guanylurea 2-chlorosulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a film which is flame retarding in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 11 An aqueous guanidine solution is prepared as in Example 1. To an equivalent solution containing 5.9 parts guanidine is added 25.2 parts 2-bromosulfanilic acid until the pH is about 7. Concentration of the solution gives guanidinium 2-bromosulfanilate.

To 9 parts of powdered nylon is added 1 part of guanidinium 2-bromosulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a film which is flame retarding in a vertical match test using a wooden match burning for sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 12 An aqueous guanylurea solution is prepared as in Example 2. To an equivalent solution containing 10.2 parts guanylurea is added 25.2 parts 2-bromosulfanilic acid until the pH is about 7. Concentration of the solution gives guanylurea 2-bromosulfanilate.

To 9 parts of powdered nylon is added 1 part of guanylurea 2-bromosulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a film which is flame retarding in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE 13 An aqueous guanidine solution is prepared as in Example 1. To an equivalent solution containing 5.9 parts guanidine is added 31.1 parts tetrachlorosulfanilic acid until the pH is about 7. Concentration of the solution yields guanidinium tetrachlorosulfanilate.

To 9 parts of powdered nylon is added 1 part of guanidinium tetrachlorosulfanilate, and the resulting mixture is made homogeneous by tumbling. A sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to give a film which is self-extinguishing in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment. An untreated nylon film is consumed in this test.

EXAMPLE l4 resulting mixture is made homogeneous by tumbling. A 7

sample is pressed between aluminum sheets at 275 C. on a hot press for 1 minute. The resulting nylon film is cooled and removed from the aluminum sheets to ive a film which 15 self-extinguishing in a vertical match est using a wooden match burning for 15 sec. in a draftfree environment. An untreated nylon film is consumed in this test.

EXAMPLE l5 Guanidinium sulfanilate is prepared as in Example 1. To 9 parts of powdered 66 nylon is added 1 part of guanidinium sulfanilate, and the resulting mixture is melt-blended to a homogeneous melt at 275 C. From the melt is spun nylon fiber which is flame retarding in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment.

EXAMPLE 16 Guanylurea 2,5-dichlorosulfanilate is prepared as in Example 4. Sixty-nine parts guanylurea 2,5-

dichlorosulfanilate and 5 parts 50 percent sodium hydroxide are heated with 800 parts water near reflux for 6 minutes prior to cooling which yields a mixture of guanylurea 2,5-dichlorosulfanilate and partially hydrolyzed material which melts mostly between C. This mixture is melt-blended into nylon 66 in 5 percent concentration at 275 C. and then pressed into a film. The film is cut into very thin pieces and subsequently spun into fabric which is flame retarding in a vertical match test using a wooden match burning for 15 sec. in a draft-free environment.

What is claimed is:

1. Compounds having the general formula:

wherein Xis Cl or Br, n is a positive integer from 0 to 4. 2. The compound having the formula of claim 1, guanylurea 2,5-dichlorosulfanilate.

Po- UNITED STATES PATENT ()Fflum CERTIFICATE OF CORRECTION Patent: No. ,2 ,658 Dated Bebruary 27, 1973 Inventofls) John C. Summers It is certified that error appears in the above-identified patent and that said Letters Patent are hereby correctad as shown below:

2 N R ll Column-8, 11mg 45, H N-C-N H2 7 N v C-NH Y 2 should read H ;,\;-C-N\ sigma 5H8 eaid this 20th day or November 1973.

' (SEAL) Attest:

EDWARD M'.FLETCI1ER3JR m Attesting Officer Acting Commissioner bf Pathdfi 22 33 UNITED STATES PATENT OFFICE CERTIFICATE OF CGRRECTION Patent No. ,1 ,65 Dated Bebruary 27, 1973 Inventor(s) John C. Summers It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

2 N R e ll Column'8, 11m; 45, H N-CN 4 0 N2 NH ll 2 should read H 1-C-N\ sigma aria-M166 this 20th dj or November 1973.

' (SEAL) Attest: v

EDWARD Mmmficfififigm. I Attesting Officer Acting Commissioner of Pathfio 

2. The compound having the formula of claim 1, guanylurea 2,5-dichlorosulfanilate. 